Lock



E. M. BENHAM LOCK Filed June 12. 1926 ATTORNEY April 3, 1928.

Patented Apr. 3, 1928.

- UNITED STATES PATENT OFFICE.

EDGAR M. IBENHAM, or nonwoon, OHIO, As'sIeNo R TO THE MOSLER or covme'ron', KENTUCKIA CORPORATION on OHIO.

LOCK COMPANY,

LOCK.

. Application filed June 12,

.- better.

The principal object of my invention is to provide a lock construction which g ves added security against picking and against manipulation by unauthorized persons, or in an unauthorized manner. Another object of my invention is to provide means of the character referred to, which may be applied to looks of difierent types and constructions,

and at the same time to provide this added protection, without complicating the construction or rquiring extensive-change and rearrangement of the usual construction. Other objects of my invention will be in part obvious and in part pointed out hereinafter.

In accordance with my invention, I provide means which prevent the master key from being moved home in its key tube until the proper guard key has been placed in the lock and turned. \Vhen the construction permits the master key to be moved home in its key tube without the application of the guard key, it permits the proper alignment of the master key with the master tumblers, so that if in any way the guard tumblers may be set up by an unauthorized person, or by means of an unauthorized instrument, the lock may be unlocked by merely turning the master key. When, as is contemplated by my invention, the master key cannot be moved home until a certain protecting tumbler has been operated by means of the guard key, added protection is given, because this particular tumbler must be set up as well as the guard tumblers before the master key can be placed even in proper position for setting up the master tumblers. This tumbler, which prevents the master key from being moved home in the key tube, is preferably disposed next to the bolt bar, to render it more inaccessible. If desired, this protecting tumbler may also function as a guard tumbler, although this additional function may be omitted.

In order that a clearer understanding of my invention may be had, attention is here- 1926. Serial No. 115,441.

bydirected to the accompanying drawings, forming-a part of this application'and illustrating one possible embodiment of my invention.

Referring tothe-drawings, Fig. 1 is a side no view of a lock embodying my'invention, drawn to approximately half size;'Fig. 2 is a sectional view thereof, and is taken on the line 2-2 of Figs. 1 and 5; Fig. 3is a view similar to Fig. 2, but shows the guard key 6 turned to set up the protecting tumbler; Fig. 4 is a view similar to Figs. 2 and 3, but shows the lock in unlocked condition; Fig. 5 is a sectional view of the same, and is taken on the line 55 ofFig. 2; Fig. 6 is anen- 17o larged sectional view of the front end of the lock, showing the protecting tumbler in set up position; and Fig. 7 is a top elevation of the bolt'bar taken separately.

Similar reference characters refer to similar parts throughout the several views of the drawings. .7,

Referring to the drawings, the lock comprises a suitable case or housing 1, provided with cover plate 2. slidable in the case, is of usual construction and includes a bolt portion 4; extendin through a suitable aperture in the case, and has a locking stump 5 behind the bolt portion 4. The lock case carries tube 6, at the inner end of which isdisposed the usual cam 7 which seats in the cam recess 8 in the bolt bar, whereby the bolt bar is operated. The case is also provided with the usual guard key tube 9. Immediately 00 over the bolt bar is disposed the protecting tumbler 10, which is pivoted on the tumbler post 11 of the lock, and has a portion 12, which, in the normal position of this tumbler, comes closely against the front side 9 of the master key tube 6 and in the path of movement of the master key 13 inwardly of its key tube, so as to prevent the master key from moving home in its key tube until this portion 12 of tumbler 10 shall have 1007 been removed from its path. The usual master and guard tumblers are positioned intermediate this protecting tumbler 10 and the cover plate 2, only one of these tumblers 14 being shown, the others being omitted 1 5 key is placed in its key tube 9 and turned. 1 9

The bolt bar 3, which is so a master key 95 The protecting tumbler 10 is so shaped that when the guard key has been turned to set up the guard tumblers, the obstructing portion 12 will be removed from the path of themaster key 13, and this key may then be moved home in its key tube and turned to unlock the look.

In the drawings, the protecting tumbler 10 is shown to extend forwardly, as at 18,

to the locking stump 5, and also acts as a 21rd tumbler for preventing retraction of thebolt bar by any means until this tumbler shall have been set up. As, shown, a spring 19, of usual construction, normally maintains the protecting tumbler 10 in protecting position. a i

It "will be noted that in the drawings, Figs.

' 2 and 5 show the guard key 17 in place, butnot turned, and accordingly, the portion 12 of the protecting tumbler 10 prevents the master key from moving home in its key tube 6., Fig. 3 shows the guard key 17 turned in its key tube 9, thus setting up the protectingtumbler l0 and removing the portiOn 12 thereof from the path of the main key 13, thus permitting movement of the main, key all the wayinto the lock. Now the main key 13 may be turned to unlock the look, as shown in Fig. 4:, meanwhile setting upt-hemaster tumblers, such as 14.

From the above it will be readily ap parent that the lock is provided with added cent the. top of the guard June, 1926.

be interpreted as illustrative a-nd not, in a limiting sensex What :I claimdsz V Ina lock of the character combination, amaster key tube, a guard key tube, a tumbler pivoted approximately at its midpoint intermediate said key tubes and having an obstructing portion normally positioned closely adjacent the front of the master key tube, whereby iiull movement of a master key into the master key tube is prevented, said tumbler having-a port-ion adjaable bya guard key in the guard key tu whereby said tumbler may be pivotedto withdraw said obstructing portion thereof,

out of the path of movement of a master key 1 into the master key tube.

This specification signed this 7th day of" EDGARM. BENHAM.

described, f in iey tube engagi- 

